Secondary Battery Electrolyte Additive for Water Scavenging and Fast Charging
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Solution Overview
Problem
Existing secondary batteries face challenges in achieving a long service life, good charging performance, and effective water management due to high water absorption by the positive electrode active material, leading to increased direct current resistance and impaired performance.
Innovation Solution
A secondary battery design incorporating a compound with an isocyanate group in the electrolyte solution, determined by the BET specific surface area, mass fraction of the positive electrode active material, and coating areal density, to moderate the isocyanate content, effectively removing water and reducing direct current resistance without affecting charging performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the positive electrode active material with high specific surface area is used to improve charging performance, then the charging performance is improved, but the water absorption increases leading to increased direct current resistance
Solution Approach 1:
The patent introduces a compound containing an isocyanate group as an intermediary substance in the electrolyte solution. This compound acts as a water scavenger that reacts with water molecules absorbed by the positive electrode active material, forming a solid electrolyte interface film. The isocyanate group (−NCO) serves as the active functional group that chemically binds with water, effectively removing harmful water from the battery system while maintaining the high specific surface area benefits of the positive electrode material.
2Object-affected harmful factors
If a compound containing isocyanate group is added to remove water, then water removal capability is improved, but the direct current resistance increases significantly
Solution Approach 1:
The patent optimizes the concentration parameter of the isocyanate group within a specific range (0.01 wt% to 5 wt%). By precisely controlling this parameter, the patent achieves effective water removal while preventing excessive direct current resistance. The optimized concentration ensures sufficient isocyanate groups are available to react with water molecules, yet maintains adequate ionic conductivity for charge transfer.
Solution Approach 2:
The patent creates a composite electrolyte system combining the isocyanate-containing compound with conventional electrolyte components (cyclic carbonates, chain carbonates, and lithium salts). This composite approach allows the isocyanate compound to perform water removal functions while the conventional electrolyte components maintain ionic conductivity, achieving synergistic effects that resolve the contradiction between water removal and electrical performance.
3Object-affected harmful factors
If the content of isocyanate compound is increased to remove more water, then water removal is enhanced, but the charging performance deteriorates due to high impedance
Solution Approach 1:
The patent establishes an optimized concentration range for the isocyanate compound (0.01 wt% to 5 wt%) that balances water removal capability with charge transfer efficiency. Within this parameter range, sufficient isocyanate groups are present to scavenge water effectively, while the ionic conductivity remains adequate to maintain good charging performance. Exceeding this range would lead to excessive impedance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the battery's cycling and storage performance, improving high-temperature cycling and storage capabilities while maintaining good charging performance by controlling the isocyanate group content.
Implementation Method 1
The additive includes a compound containing an isocyanate group... the content of the compound containing the isocyanate group in the electrolyte solution is moderate, so that not only can the water in the electrolyte solution of the secondary battery be effectively removed
Data Source
Figure 1~3
AI summary
The present application provides a secondary battery. The secondary battery comprises a positive electrode plate, a negative electrode plate, and an electrolyte solution. The positive electrode plate comprises a positive electrode film layer. The positive electrode film layer contains a positive electrode active material. The electrolyte solution comprises a solvent, a lithium salt, and an additive. The additive includes a compound containing an isocyanate group. The mass fraction of the compound containing the isocyanate group in the electrolyte solution is a, with 11 ≤ n/10000a ≤ 96600 where n = b × c × d; n is the real surface area of the positive electrode active material per unit apparent surface area; b is the BET specific surface area of the positive electrode active material, in cm2/g; c is the mass fraction of the positive electrode active material in the positive electrode film layer; and d is the coating areal density of the positive electrode film layer, in g/ cm2. The present application further relates to a corresponding electrical apparatus. The secondary battery can effectively remove water from the electrolyte solution, resulting in not only a good cycling performance and storage performance but also a relatively good charging performance.